1589P - Prognostic impact of tumor-infiltrating lymphocytes (TILs) in male breast cancer

Abstract

The presence of tumor-infiltrating lymphocytes (TILs) has been shown to have significant prognostic relevance for certain subtypes of female breast cancer. However, whether TILs have any indication for prognosis in male breast cancer (MBC) patients remains unknown. The aim of this study was to evaluate the prognostic value of TILs in MBC. We retrospectively identified 120 male breast cancer patients diagnosed between 2000 and 2013 at Salah Azaïz National Cancer Institute. Two pathologists independently evaluated TIL levels using H&E-stained slides following 2014 International TILs Working Group guidelines. Samples were classified as: low-TILs (≤ 5), intermediate-TILs (10-50) and Lymphocyte Predominant Breast Cancer (LPBC) (≥ 60%). Prognostic significance of TILs and overall survival (OS) was assessed by Kaplan-Meier analysis and log-rank test. Subtyping revealed 51 Luminal A (42.5%), 57 Luminal B (47.5%), 2 HER2-enriched (1.7%) and 10 TNBC tumors (8.3%). The median for presence of stromal TILs (sTILs) was 10.8% (1%-40%). 63 (52.5%) had low sTILs and 57 (47.5%) had moderate sTILs. No LPBC were identified. TNBC subtype (13.1% [5%-25%]) and HER2-enriched tumors (14% [13%-15%]) compared with Hormone receptor-positive tumors (10.0% [5.0%-22.5%]) had higher median levels of TILs at diagnosis. On univariate analysis, higher levels of TILs were associated with better OS (p = 0.04) and HER2 (p = 0.05). There was no significant difference between levels of TILs according to lymph node status (p = 0.39), tumor size (p = 0.16) or grade (p = 0.77). Multivariate analyses indicated that Higher levels of TILs were an independent prognostic factor for OS (p = 0.05). High TILs is a favorable prognostic factor in MBC patients. Low-TILs seemed to be associated with worst overall survival suggesting a more aggressive phenotype in MBC patients. These results show that TILs may represent a novel MBC marker with prognostic significance that could be included into the limited marker panels for MBC.